Methods and apparatuses for deploying minimally-invasive heart valves

ABSTRACT

A system for delivering and deploying a self-expandable heart valve to a site of implantation such as the aortic annulus includes a deployment mechanism that engages the valve and regulates the rate of expansion of both the proximal and distal ends thereof. The heart valve may be a rolled-type valve and the deployment mechanism may include a plurality of distal fingers and a plurality of proximal fingers that engage the outer layer of the heart valve. Controlled radial movement of the fingers regulates the unwinding of the rolled heart valve. The fingers may be removed prior to inflation of a balloon to fully expand the valve, or the fingers may be repositioned to the inside of the valve for this purpose. The deployment mechanism may include an umbrella structure that forces the rolled valve outward into its fully expanded configuration. Alternatively, a gear shaft that engages one or more gear tracks on the valve may be utilized to regulate expansion of the valve. A stabilization balloon may be used to axially and radially locate the deployment mechanism relative to the site of implantation. Methods of operation of the delivery and deployment mechanism include regulating the rate of self-expansion of the valve and forcing the valve outward into its fully expanded configuration utilizing the same or different means.

FIELD OF THE INVENTION

[0001] The present invention relates generally to medical devices andparticularly to methods and devices for deploying expandable heart valveprostheses especially for use in minimally-invasive surgeries.

BACKGROUND OF THE INVENTION

[0002] Prosthetic heart valves are used to replace damaged or diseasedheart valves. In vertebrate animals, the heart is a hollow muscularorgan having four pumping chambers: the left and right atria and theleft and right ventricles, each provided with its own one-way valve. Thenatural heart valves are identified as the aortic, mitral (or bicuspid),tricuspid and pulmonary valves. Prosthetic heart valves can be used toreplace any of these naturally occurring valves.

[0003] Where replacement of a heart valve is indicated, thedysfunctional valve is typically cut out and replaced with either amechanical valve or a tissue valve. Tissue valves are often preferredover mechanical valves because they typically do not require long-termtreatment with anticoagulants. The most common tissue valves areconstructed with whole porcine (pig) valves, or with separate leafletscut from bovine (cow) pericardium. Although so-called stentless valves,comprising a section of porcine aorta along with the valve, areavailable, the most widely used valves include some form of stent orsynthetic leaflet support. Typically, a wireform having alternatingarcuate cusps and upstanding commissures supports the leaflets withinthe valve, in combination with an annular stent and a sewing ring. Thealternating cusps and commissures mimic the natural contour of leafletattachment.

[0004] A conventional heart valve replacement surgery involves accessingthe heart in the patient's thoracic cavity through a longitudinalincision in the chest. For example, a median sternotomy requires cuttingthrough the sternum and forcing the two opposing halves of the rib cageto be spread apart, allowing access to the thoracic cavity and heartwithin. The patient is then placed on cardiopulmonary bypass whichinvolves stopping the heart to permit access to the internal chambers.Such open heart surgery is particularly invasive and involves a lengthyand difficult recovery period.

[0005] Recently, a great amount of research has been done to reduce thetrauma and risk associated with conventional open heart valvereplacement surgery. In particular, the field of minimally invasivesurgery (MIS) has exploded since the early to mid-1990s, with devicesnow being available to enable valve replacements without opening thechest cavity. MIS heart valve replacement surgery still typicallyrequires bypass, but the excision of the native valve and implantationof the prosthetic valve are accomplished via elongated tubes (cathetersor cannulas), with the help of endoscopes and other such visualizationtechniques. Some examples of recent MIS heart valves are shown in U.S.Pat. No. 5,411,552 to Anderson, et al., U.S. Pat. No. 5,980,570 toSimpson, U.S. Pat. No. 5,984,959 to Robertson, et al., PCT PublicationNo. 00/047139 to Garrison, et al., and PCT Publication No. WO 99/334142to Vesely.

[0006] The typical MIS valve of the prior art includes a directlyradially expanding stent that is initially compressed for deliverythrough a cannula, and is then expanded at the site of implantationafter removing the constraint of the cannula. The expansion isaccomplished using an internal balloon catheter around which the stentis compressed.

[0007] Despite various delivery systems for conventional MIS valves,there remains a need for a delivery system that more reliably controlsthe expansion of new MIS valves.

SUMMARY OF THE INVENTION

[0008] In accordance with a preferred embodiment, the present inventionprovides a system for delivering and deploying an expandable prostheticheart valve, comprising a catheter shaft having a proximal end and adistal end and a lumen therethrough extending along an axis. The heartvalve deployment mechanism extends axially from the distal end of thecatheter shaft, and includes spaced apart proximal and distal deploymentmembers. An actuating shaft extends through the lumen of the cathetershaft and operates to actuate at least one of the proximal and distaldeployment members. The deployment members may be radially movable andcomprise fingers each pivoted at one end thereof to the deploymentmechanism. There are desirably at least two proximal deployment fingersand at least two distal deployment fingers, wherein the deploymentfingers are axially movable. The deployment members may be radiallymovable and there are two of the actuating shafts. A first actuatingshaft operates to radially displace the proximal deployment members anda second actuating shaft operates to radially displace the distaldeployment members, wherein the first and second actuating shafts areconcentrically disposed to slide with respect one another.

[0009] In one embodiment the deployment mechanism comprises a proximalcollet with respect to which the proximal deployment members pivot, anda distal collet with respect to which the distal deployment memberspivot, wherein the proximal collet and distal collet are relativelyaxially movable. A first actuating shaft extends within a cavity in theproximal collet and a first driver attaches thereto that acts upon theproximal deployment members to pivot them with respect to the proximalcollet. A second actuating shaft extends through the first actuatingshaft and into a cavity in the distal collet and a second driverattaches thereto that acts upon the distal deployment members to pivotthem with respect to the distal collet.

[0010] There are various ways to actuate the deployment members. First,each deployment member may pivot about a point that is fixed withrespect to the associate collet and includes structure that engagescooperating structure on the associated driver, wherein axial movementof the driver rotates the structure about the pivot point, thus rotatingthe deployment member. Alternatively, each deployment member has a pinfixed with respect thereto that is received within a corresponding slotin the associated driver, and each collet includes a plurality of pinsfixed with respect thereto that are received within corresponding slotsin the associated deployment members. In the alternative configuration,axial movement of the driver displaces the pins fixed with respect tothe deployment members and causes the deployment members to pivotoutward due to a camming action of the deployment member slots over thecollet pins.

[0011] In a still further embodiment, each deployment member maycomprise a pad that is coupled to a respective proximal and distal endcap disposed along the catheter shaft, the pads being radiallydisplaceable with respect to the associated end cap, wherein theproximal and distal end caps are axially movable with respect to eachother. There may be two of the actuating shafts, each shaft controllinga plurality of flexible tongs having column strength that extend betweenone of the end caps and attach to the associated pads, wherein axialmovement of each shaft shortens or lengthens the radial extent of theflexible tongs controlled thereby so as to radially displace theattached pads.

[0012] Still further, each deployment member may comprise a gear thatengages a gear track on the heart valve.

[0013] The system preferably includes a stabilization balloon on thecatheter shaft proximal to the deployment mechanism and sized to expandand contact a surrounding vessel adjacent the site of implantation. Thestabilization balloon may be shaped so as to permit blood flow past itin its expanded configuration, such as with multiple outwardly extendinglobes.

[0014] The heart valve deployment mechanism may be a modular unitcoupled to the distal ends of the catheter shaft and actuating shaft.

[0015] In another aspect of the invention, a system for delivering anddeploying a self-expandable prosthetic heart valve to a site ofimplantation is provided. The system comprises a catheter for advancingthe heart valve in a contracted configuration to the site ofimplantation; means on the catheter for permitting the heart valve toself-expand from its contracted configuration to an initial expandedconfiguration in contact with the surrounding site of implantation; andmeans for regulating the rate of self-expansion of the heart valve. Thesystem may also include means for expanding the heart valve from itsinitial expanded configuration to a final expanded configuration, suchas a balloon. Alternatively, the means for expanding the heart valvefrom its initial expanded configuration to a final expandedconfiguration may be the same as the means for regulating the rate ofself-expansion of the heart valve.

[0016] The means for expanding the heart valve from its initial expandedconfiguration to its final expanded configuration and the means forregulating the rate of self-expansion of the heart valve may comprise agear mechanism that engages both the distal and proximal ends of theheart valve. If the heart valve is of the rolled type having multiplewound layers, the gear mechanism may have a gear shaft that engages aninner layer of the spirally wound heart valve and a retaining bar thatengages an outer layer of the spirally wound heart valve, wherein thedistance between the gear shaft and retaining bar is adjustable.

[0017] Another aspect of the invention is a system for delivering anddeploying an expandable prosthetic heart valve to a site ofimplantation, comprising a catheter for advancing the heart valve in acontracted configuration to the site of implantation, and astabilization device provided on the catheter sized to expand andcontact a surrounding vessel adjacent the site of implantation. Thesystem also has means on the catheter distal to the stabilization devicefor expanding the heart valve from its contracted configuration to aninitial expanded configuration in contact with the surrounding site ofimplantation. The stabilization device may be a balloon shaped so as topermit blood flow past it in its expanded configuration, such as forexample with multiple outwardly extending lobes.

[0018] A method for delivering and deploying a self-expandableprosthetic heart valve to a site of implantation is also provided by thepresent invention. The method comprises: advancing the heart valve in acontracted configuration to the site of implantation; permitting theheart valve to self-expand from its contracted configuration to aninitial expanded configuration in contact with the surrounding site ofimplantation; and regulating the rate of self-expansion of the heartvalve.

[0019] In the preferred method, the step of advancing the heart valve ina contracted configuration to the site of implantation comprisesproviding a heart valve deployment mechanism that in one operating modemaintains the heart valve in the contracted configuration, and inanother operating mode regulates the rate of self-expansion of the heartvalve. The heart valve deployment mechanism may have a plurality ofproximal deployment members that engage a proximal end of the valve, anda plurality of distal deployment members that engage a distal end of thevalve, and wherein coordinated radial movement of the proximal anddistal deployment members regulates the rate of self-expansion of theheart valve. Alternatively, the heart valve deployment mechanismincludes a gear shaft having a plurality of gear teeth that engage agear track provided on the heart valve, wherein the rate ofself-expansion of the heart valve is regulated by regulating therotational speed of the gear shaft.

[0020] The preferred method further includes expanding the heart valvefrom its initial expanded configuration to a final expandedconfiguration. Also, a catheter-based valve deployment mechanism may beprovided having deployment members that both regulate the rate ofself-expansion of the heart valve and expand the heart valve from itsinitial expanded configuration to its final expanded configuration.Alternatively, a catheter-based valve deployment mechanism maybeprovided having deployment members that regulate the rate ofself-expansion of the heart valve, and an inflation balloon expands theheart valve from its initial expanded configuration to its finalexpanded configuration. In the latter case, the valve inflation balloonis separate from the deployment mechanism and is introduced into thevalve after at least a partial expansion thereof. The method furtherdesirably includes stabilizing the heart valve in its contractedconfiguration adjacent the site of implantation prior to permitting theheart valve to self-expand. The step of stabilizing the heart valve mayinvolve inflating a stabilization balloon, and also permitting bloodflow past the inflated stabilization balloon.

[0021] A further understanding of the nature and advantages of theinvention will become apparent by reference to the remaining portions ofthe specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is an elevational view of an exemplary expandable heartvalve delivery and deployment system of the present invention with acatheter shaft shown broken so as to illustrate the main componentsthereof;

[0023]FIG. 2 is a perspective view of the distal end of the deliverysystem of FIG. 1 showing a heart valve in its expanded configuration;

[0024]FIG. 3A is a longitudinal sectional view through a portion of thedistal end of the delivery and deployment system of FIG. 1 illustratingpart of a mechanism for controlling the expansion of a heart valve,which is shown in its contracted configuration;

[0025]FIG. 3B is a longitudinal sectional view as in FIG. 3A showing theheart valve expanded;

[0026]FIG. 4 is a perspective view of the distal end of an alternativeheart valve delivery and deployment system of the present inventionshowing a heart valve in its contracted configuration;

[0027]FIG. 5A is a perspective view of the delivery and deploymentsystem of FIG. 4 showing the heart valve in its expanded configurationand an inflated stabilization balloon;

[0028]FIG. 5B is a perspective view as in FIG. 5A illustrating a finalstep of deployment of the heart valve;

[0029]FIG. 6A is an enlarged elevational view of a portion of the distalend of the delivery and deployment system of FIG. 4;

[0030]FIG. 6B is an enlarged longitudinal sectional view of the portionof the distal end of the delivery and deployment system seen in FIG. 6A;

[0031] FIGS. 7A-7F are perspective views showing a number of steps inthe delivery and deployment of an expandable heart valve using thesystem of FIG. 4;

[0032]FIG. 8 is a perspective view of the distal end of a secondalternative delivery and deployment system of the present inventionshowing a heart valve in its expanded configuration;

[0033]FIG. 9 is a perspective view of the distal end of the secondalternative delivery and deployment system shown as in FIG. 8 withoutthe heart valve;

[0034]FIG. 10 is a perspective view of the distal end of the deliveryand deployment system of FIG. 8 shown in a mode of operation thatexpands the heart valve outward into a locked position;

[0035]FIG. 10A is an enlarged sectional view of a portion of the distalend of the second alternative delivery and deployment system as takenalong line 10-10A of FIG. 10;

[0036] FIGS. 11A-11F are perspective views showing a number of steps inthe delivery and deployment of an expandable heart valve using thesystem of FIG. 8;

[0037]FIG. 12 is a perspective view of the distal end of a thirdalternative delivery and deployment system of the present invention thatutilizes a gearing mechanism and showing a heart valve in its expandedconfiguration;

[0038]FIG. 12A is an enlarged sectional view of a portion of the distalend of the third alternative delivery and deployment system as takenalong line 12A-12A of FIG. 12;

[0039]FIG. 13 is an enlarged perspective view of a portion of thedelivery and deployment system of FIG. 12 shown without the heart valve;and

[0040]FIG. 14 is a plan view of a stent of an expandable heart valve ofthe present invention for use with the third alternative delivery anddeployment system as seen in FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] The present invention discloses a number of expandable heartvalves for implantation in a host annulus, or host tissue adjacent theannulus. The valves may be implanted in any of the four valve positionswithin the heart, but are more likely to be used in replacing the aorticor mitral valves because of the more frequent need for such surgery inthese positions. The patient may be placed on cardiopulmonary bypass ornot, depending on the needs of the patient.

[0042] A number of expandable prosthetic heart valves are disclosed inco-pending U.S. application Ser. No. 09/815,521 that are initiallyrolled into a tight spiral to be passed through a catheter or other tubeand then unfurled or unrolled at the implantation site, typically avalve annulus. These will be denoted “rolled heart valves” and compriseone- or two-piece sheet-like stent bodies with a plurality ofleaflet-forming membranes incorporated therein. Various materials aresuitable for the stent body, although certain nickel-titanium alloys arepreferred for their super-elasticity and biocompatibility. Likewise,various materials may be used as the membranes, including biologicaltissue such as bovine pericardium or synthetic materials. It should alsobe noted that specific stent body configurations disclosed herein or inU.S. application Ser. No. 09/815,521 are not to be considered limiting,and various construction details may be modified within the scope of theinvention. For example, the number and configuration of lockout tabs (tobe described below) may be varied.

[0043] As a general introduction, the heart valves in a first,spirally-wound or contracted configuration are delivered through a tubesuch as a percutaneously-placed catheter or shorter chest cannula andexpelled from the end of the tube in the approximate implantationlocation. The heart valve is then expanded into a second, unwound orexpanded configuration that engages the native host tissue, such as thetarget valve annulus. Depending on the native valve being replaced, theprosthetic heart valve may have varying axial lengths. For example, inthe aortic position, an outflow portion of the valve may extend upwardinto and even flare out and contact the aorta to better stabilize thecommissure regions of the valve. In other words, the particular designof the valve may depend on the target valve location.

[0044] The present invention is particularly adapted for delivering anddeploying self-expandable rolled heart valves, although those of skillin the art will recognize that certain embodiments may be adapted fordeploying plastically deformable rolled heart valves. Self-expandablestents in general are known, typically constructed of a tubular metallattice that has a normal, relaxed diameter and is compressed forinsertion into a vein or artery. Upon expulsion from the end of acatheter, the tubular metal lattice expands to its original largerdiameter in contact with the vessel wall. It is important to note thatthere is no regulation of the self-expansion of the stent, as the tubereliably assumes its larger shape.

[0045] A number of embodiments of the present invention will now bedescribed with reference to the attached drawings. It should beunderstood that the various elements of any one particular embodimentmay be utilized in one or more of the other embodiments, and thuscombinations thereof are within the scope of the appended claims.

[0046]FIG. 1 illustrates an exemplary system 20 for delivering anddeploying an expandable heart valve. The main elements of the system 20include a proximal operating handle 22, a catheter shaft 24 extendingdistally from the handle and shown broken to fit on the page, a heartvalve deployment mechanism 26, and a guidewire 28 typically extendingentirely through the system. The expandable heart valve 30 is seen heldin a contracted configuration between a distal collet body 32 and aproximal collet body 34 of the deployment mechanism 26. The system mayfurther include a stabilization balloon 36 provided on the cathetershaft 24 just proximal the deployment mechanism 26.

[0047] Prior to describing the exemplary deployment mechanism 26, andalternative mechanisms, in greater detail, an overview of the techniquesfor using the system 20 is appropriate. For this discussion, it will beassumed that the heart valve 30 will be implanted in the aorticposition.

[0048] Prior to introduction of the distal end of the system 20 into thepatient, the expandable heart valve 30 is selected based on ameasurement of the aortic annulus. Various sizing methodology areavailable, a discussion of which is outside the scope of the presentinvention. The selected heart valve 30 may be initially wound into atight spiral in its storage container, or it may be stored expanded andthen wound into its contracted configuration just prior to use. For thispurpose, co-pending U.S. application Ser. No. 09/*, entitled Containerand Method for Storing and Delivering Minimally-Invasive Heart Valves,filed Aug. 30, 2001, which is expressly incorporated herein, may beused. That application discloses a system for storing and thenautomatically converting an expandable valve into its contracted shapewhile still in the storage container. Additionally, the valve 30 may bestored along with the deployment mechanism 26 as a modular unit. In thatcase, the deployment mechanism 26 and valve 30 may be snapped onto orotherwise coupled with the distal end of the catheter shaft 24. Thisenables one operating handle 22 and catheter shaft 24 to be used with anumber of different valve/deployment mechanism units. After those ofskill in the art have an understanding of the various control oractuation shafts/cables described herein, the coupling structure shouldbe relatively straightforward, and thus a detailed explanation will notbe provided.

[0049] The guidewire 28 is first inserted into a peripheral artery, suchas the femoral or carotid, using known techniques, and advanced throughthe ascending aorta into the left ventricle. The catheter shaft 24 withthe deployment mechanism 26 on its leading or distal end is then passedover the guidewire 28, possibly with the assistance of an intermediatesized obturator, and into the peripheral vessel via the well-knownSeldinger method. The operator then advances and positions thedeployment mechanism 26 in proximity to the implantation site, in thiscase the aortic annulus, using visualization devices such as radiopaquemarkers on the deployment mechanism 26 or heart valve 30, or anendoscope. Advancement of the deployment mechanism 26 involves simplypushing the entire catheter shaft 24 along the guidewire 28 using thehandle 22. Once the valve 30 is properly positioned, the operatorexpands the stabilization balloon 36 into contact with the surroundingaorta. In this manner, the heart valve 30 is both axially and radiallyanchored with respect to the surrounding annulus to facilitate properengagement therewith. The stabilization balloon 36 may be shaped topermit blood flow in its expanded configuration for beating heartsurgeries.

[0050] Expansion of the heart valve 30 may be accomplished in variousways, as will be described in greater detail below. Operation of thedeployment mechanism 26 involves manipulation of cables, shaft, or otherelongated devices passing from the operating handle 22 through thecatheter shaft 24. These elongated devices may be utilized to transferaxial (push/pull) forces or rotational torque initiated in the handle 22to various elements of the deployment mechanism 26. The presentapplication will not focus on specific mechanisms in the handle 22 forinitiating the forces on the cables or shafts passing through thecatheter shaft 24, as numerous such apparatuses are known in the art.

[0051] Now with reference to FIG. 2, the distal end of the delivery anddeployment system 20 is illustrated with the deployment mechanism 26holding the generally tubular heart valve 30. The heart valve 30 isshown in an expanded configuration with a portion cut away to illustratea lockout balloon 40 therewithin. The heart valve 30 has a rolledconfiguration and includes a generally sheet-like stent body 42 thatunwinds from a tight spiral into an expanded tube having a distal end 44a and a proximal end 44 b. A plurality of distal deployment members orfingers 46 extending proximally from the distal collet body 32 engagethe valve body distal end 44 a, while a plurality of proximal deploymentfingers 48 extending distal from the proximal collet body 34 engage thevalve body proximal end 44 b. It should be noted that various featuresof the heart valve 30, such as the valve leaflets, are not illustratedfor clarity.

[0052] The inflated stabilization balloon 36 is shown having generally adisk-shape, although other shapes are contemplated, such as alobed-shape to permit blood flow, as will be described below. Across-section of the catheter shaft 24 illustrates a plurality of outerlumens 50 surrounding a central lumen 52. The lumens 50 may be used forinflating the balloon 36, 40, or for passing fluid or the devicestherethrough. The central lumen 52 is typically used for passage of thecables or shafts for operating the deployment mechanism 26.

[0053]FIGS. 3A and 3B illustrate in cross-section the details of thedistal end of the deployment mechanism 26, and specifically the distalcollet body 32. FIG. 3A shows the heart valve body 42 in its contractedconfiguration with multiple spirally wound layers 60 a-60 e, while FIG.3B shows the valve body 42 in its expanded configuration having only onelayer 62. The distal deployment fingers 46 each possesses a flexibleclaw 64 that directly engages the outer layer 60 a of the valve body 42.The flexible claw 64 has an-initial curved set indicated in dashed linethat applies a radially inward spring force to the valve body 42. Whenin the position of FIG. 3A, the claw 64 flexes outward into a generallyliner configuration, and helps prevent damage to the valve body by thefingers 46,48. At least two of the fingers 46, 48 on each end, andpreferably three or more, retain the valve body 42 in its spirally woundor contracted configuration during delivery through the vascular systemto the site of implantation. It should be noted also that the distalcollet body 32 has a rounded, generally bullet-shaped nose 66 thatfacilitates introduction into and passage through the vascular system.

[0054] As seen in FIG. 3A, each of the fingers 46 initially resideswithin an axial channel 70 formed in the collet body 32 and pivotsoutward in a radial plane in the direction of arrow 72 about a colletpin 74 fixed in the collet body across the channel. In the radiallyinward configuration of FIG. 3A, the fingers 46 are recessed within thechannels 70 to present a low introduction profile for the deploymentmechanism 26. Each of the fingers 46 includes a lever 76 that engages adepression 78 within a distal driver 80. The driver 80 reciprocatesaxially within a cavity 82 formed within the distal collet body 32, asindicated by the double-headed movement arrow 84. From the positionshown, proximal movement of the driver 80 with respect to the colletbody 32 acts on the lever 76 to pivot the finger 46 outward in thedirection of arrow 72. The lever 76 is shown rounded so as to easilyslide within the similarly shaped though concave depression 78. Ofcourse, other arrangements for coupling axial movement of the distaldriver 80 to rotational movement of the finger 46 are possible.

[0055] A distal driver shaft 90 extends over the guidewire 28 to befixed within a bore of the distal driver 80. Likewise, the distal colletshaft 92 is concentrically disposed about the distal driver shaft 90 andis fixed within a bore of the distal collet body 32. All these elementsare thus coaxial about the guide wire 28. Axial movement of the shafts90, 92 causes axial movement of the driver 80 and collet body 32,respectively. Collet movement is indicated by the double-headed arrow94. In the initial delivery configuration of FIG. 3A, the collet body 32is positioned distally from the distal end 44 a of the valve body 42.

[0056] In operation of the deployment mechanism 26 of FIG. 2, as bestseen in FIG. 3B, the distal driver 80 is displaced within the cavity 82by relative movement of the distal driver shaft 90 and distal colletshaft 92, and interaction between the lever 76 and depression 78 causesoutward pivoting motion of the finger 46. Because the valve body 42 isannealed into its expanded configuration, outward pivoting of thefingers 46 permits expansion thereof.

[0057] Therefore, the valve body 42 converts from its spirally woundconfiguration with multiple spirally-wound layers 60 a, 60 e as seen inFIG. 3A, to the expanded configuration of FIG. 3B having the singlelayer 62. During this expansion, contact between the flexible claws 64and the outer layer 60 a of the valve body 42 is maintained bycontrolling the relative movement between the distal driver 80 and thedistal collet body 32. This contact between the claws 64 and valve body42 regulates the speed or rate of expansion of the valve body, thuspreventing any mis-alignment problems. That is, because of the provisionof both the distal collet body 32 and proximal collet body 34, andassociated fingers 46 and 48, the rate of expansion of both the distalend 44 a and proximal end 44 b of the valve body 42 can be equilibrated.Because both ends of the valve body 42 expand at the same rate, thevalve forms a tube rather than potentially expanding into a partial coneshape.

[0058] It is important to note that during transition of the valve body42 from its contracted to its expanded configuration, the distal colletbody 32 moves in a proximal direction with respect to the valve body 42as indicated by the movement arrow 96. The reader will note thedifferent relative positions of the proximal end of the collet body 32with respect to the distal end 44 a of the valve body 42 in FIGS. 3A and3B. This collet body 32 movement results from relative movement of thedistal collet shaft 92 with respect to the valve body 42, which bodyposition is determined by the position of the proximal fingers 48, or bya supplemental shaft (not shown) coupled to the operating handle 22.Because of the proximal collet body 32 movement with respect to thevalve body 42, the flexible claws 64 maintain the same axial positionwith respect to the valve body 42 during outward pivoting of the fingers46. That is, outward pivoting of the fingers 46 causes both radiallyoutward and distal axial movement of the claws 64 with respect to colletpin 74, and the axial component of movement must be accommodated bymovement of the collet body 32 or else the claws 64 would disengage thevalve body 42. The distal collet body 32 includes a frusto-conicalproximal end 98 that facilitates displacement of the collet body intothe partially unwound valve body 42, and prevents binding therebetween.

[0059] The valve body 42 expands outward under regulation of the fingers46, 48 until it contacts the surrounding host tissue. The valve body 42has an annealed shape such that its relaxed configuration is open, withits inner and outer side edges being spaced apart. As such, the valvebody 42 will continue to expand until it contacts the surroundingtissue, as long as the final tubular size of the valve is larger thanthe site of implantation. Therefore, proper sizing of the valve isextremely important.

[0060] Once the valve body 42 contacts the surrounding tissue, it hasreached its initial expanded state. At this stage, the deploymentfingers 46, 48 remain outwardly pivoted but are moved apart by relativeaxial movement of the collet bodies 32, 34 away from each other so as todisengage the claws 64 from the distal and proximal ends 44 a, 44 b ofthe valve body 42. Once disengaged from the valve, the fingers 46, 48may be retracted into their respective channels 70. Subsequently,inflation of the lockout balloon 40 (FIG. 2) further expands the valvebody 42 into more secure engagement with the surrounding tissue untillockout features on the valve body engage and secure the valve body inits final expanded configuration. These lockout features are fullydescribed in co-pending U.S. application Ser. No. 09/815,521, whichdisclosure is hereby expressly incorporated by reference.

[0061] The lockout balloon 40 resides initially in the catheter shaft 24or even outside of the body during the first phase of expansion of thevalve body 42. Because the valve body 42 advances through thevasculature in a relatively tight spiral so as to minimize its radialprofile for minimally invasive surgeries, the lockout balloon 40 ispreferably not positioned in the middle thereof. Of course, thisconstraint is necessary only when the insertion space is limited, and ifthe surgery is open heart or otherwise not so space-limited then theballoon 40 may indeed be initially positioned inside and delivered alongwith the valve. In the preferred minimally invasive deployment, however,the balloon must be introduced within the valve body 42 after at least apartial expansion or unwinding thereof. Typically, the valve body 42expands into its initial expanded configuration in contact with thesurrounding tissue before the lockout balloon 40 advances into itsposition as seen in FIG. 2, although the balloon may be advanced intothe valve as soon as a sufficient space in the middle of the valve opensup.

[0062] The lockout balloon 40 preferably has a shape with enlarged endsand a connecting middle portion, much like a dumbbell. In this manner,the balloon acts on the proximal and distal ends of the valve body 42,without contacting a middle portion where the leaflets of the valve arelocated. Of course, other arrangements of balloon are possible, as aremultiple lockout balloons.

[0063] After the valve body 42 is fully implanted, the lockout balloon40 is deflated and the catheter shaft 24 withdrawn from the body alongthe guide wire 28. The proximal collet body 34 also has a bullet-shapedproximal end to facilitate this removal through the vasculature.

[0064] FIGS. 4-6B illustrate the distal end of an alternative expandableheart valve delivery and deployment system 100 of the present inventionthat is in many ways similar to the first-described embodiment of FIGS.1-3B. Namely, as seen in FIG. 4, the system 100 includes a deploymentmechanism 102 having a distal collet 104 with a plurality of deploymentmembers or fingers 106, and a proximal collet 108 having a plurality ofdeployment members or fingers 110. The deployment fingers 106, 110engage respective ends of a self-expandable heart valve 112, which isshown in its contracted configuration. As in the earlier embodiment, thedeployment fingers 106, 110 enable regulated self-expansion of the heartvalve 112 to ensure the valve expands to the correct tubular shape.Although there are a number of constructional differences between thetwo embodiments, the main functional difference pertains to the mannerin which flexible claws 114, 116 of the deployment fingers 106, 110 aremaintained in particular axial locations with respect to the distal andproximal ends 118 a, 118 b, respectively, of the valve 112. In thefirst-described embodiment, the collets 32, 34 were axially displacedalong with the drivers 80, thus necessitating axial movement andcoordination of four different shafts, while in the embodiment of FIGS.4-6B movement of only two shafts are needed. This modification willbecome clear below.

[0065]FIG. 4 illustrates a stabilization balloon 120 in its folded ordeflated configuration just proximal to proximal collet 108. FIG. 5Ashows the stabilization balloon 120 inflated and assuming a four-lobedstar shape. The entire distal end of the system 100 is positioned at thedistal end of a catheter shaft 122 and travels over a guide wire 124.The stabilization balloon 120 is sized to expand and contact asurrounding vessel adjacent the site of implantation, such as theascending aorta. The star shape of the stabilization balloon 120 permitsblood flow in the expanded configuration of the balloon for beatingheart surgeries, though of course other balloon shapes could be used.Furthermore, devices other than a balloon for stabilizing the distal endof the system 100 may be utilized. For example, a mechanical expandingstructure having struts or a wire matrix may work equally as well as aballoon and also permit blood flow therethrough. Therefore, the termstabilization device refers to all of the above variants.

[0066]FIG. 5A also illustrates the heart valve 112 in its initialexpanded configuration such that a plurality of leaflet mounting windows126 are visible. In this case, the leaflets are not shown for clarity soas to expose a distal collet shaft 128 extending through the middle ofthe valve between the proximal and distal collets 104, 108. The heartvalve 112 is permitted to expand into the shape shown in FIG. 5A byoutward pivoting of the respective flexible claws 114, 116 of thedeployment fingers 106, 110. This pivoting occurs by proximal movementof a distal driver 130 with respect to the distal collet 104, and distalmovement of a proximal driver 132 with respect to the proximal collet104. The change in the relative positions of the drivers 130, 132 andcollets 104, 108 may be seen by comparison of FIG. 4 and FIG. 5A.

[0067]FIG. 5B shows the deployment mechanism 102 during a valvedeployment phase that converts the valve 112 from its initial expandedconfiguration to a final expanded or locked out configuration. Thedeployment fingers 106, 110 have been displaced so that they residewithin the tubular valve 112 and are then in a position to be once againpivoted outward, as indicated by the arrows 134, into contact with thevalve. In this case, therefore, a separate lockout balloon within thevalve 112, such as balloon 40 in FIG. 1, may not be necessary, unlessthe additional expansion force is required. A full sequence of operationof the deployment system 100 will be described below with respect toFIGS. 7A-7F after an exemplary construction of the system is explained.

[0068]FIGS. 6A and 6B illustrate, in elevational and sectional views,respectively, the proximal end of the deployment system 102 with thefingers 110 pivoted open to an intermediate position during the stage ofself-expansion of the valve 112 from its contracted configuration to itsinitial expanded configuration. The flexible claws 116 are shown incontact with the exterior of the valve body 112, with their curved setshown in phantom. The direction of movement of the fingers 110 isindicated in both views by the movement arrow 136.

[0069] With specific reference to FIG. 6B, the collet 108 includes acentral through bore (not numbered) that slidingly receives the distalcollet shaft 128. The distal collet shaft 128, in turn, slidinglyreceives a distal driver shaft 140, which directly travels over theguidewire 124. Each of the deployment fingers 110 resides within anaxial collet channel 144 that extends from the distal end of the collet108 into proximity with a cavity 146 located on the proximal end. Theproximal driver 132 reciprocates within the cavity 146 and includes athrough bore (not numbered) that slides over a tubular boss 148extending proximally from the collet 108. The driver 132 includes aproximal tubular flange 150 that closely receives and is fixed withrespect to a proximal driver shaft 152. A proximal collet shaft 154mounts to the exterior of the tubular boss 148 of the collet 108, and isadapted to slide within the proximal driver shaft 152. By virtue of thefour shafts 128, 140, 152, and 154, the collets 104, 108 and drivers130, 132 may be axially displaced with respect to one another.

[0070] The proximal collet 108 carries a plurality of collet pins 116that are fixed across an approximate midpoint of each of the colletchannels 144 and are received within curved finger cam slots 162. Asmentioned previously, two, and preferably three fingers 110 are requiredfor reliable regulation of the self expansion of the valve 112, andthere are an equivalent number of collet channels 144 and pins 160. Thefinger cam slots 162 are disposed in the middle of each finger 110, andthe finger also carries a pin 166 fixed to its proximal end. As seenbest in FIG. 6A, each finger pin 166 travels along a curvilinear colletcam slot 168. The finger pins 166 are each also constrained by a lineardriver travel slot 170 that is best seen in FIG. 6B. With referenceagain to FIG. 6A each finger 110 includes a flange portion 172 that isreceived in a driver channel 174 formed between bifurcated walls 176 ofthe proximal driver 132. The driver travel slot 170 is thus formed inboth walls 176.

[0071] Movement of the various components of the proximal end of thedeployment mechanism 102 is depicted in FIG. 6B. The outward pivotingmotion of the finger 110 is indicated by arrow 136. The outward fingermovement is accomplished by distal movement of the finger 110 withrespect to the collet pin 160 which travels from the upper right end ofthe finger cam slot 162 to the lower left end. Because the collet pin160 is fixed with respect to the collet 108, the finger 110 movesoutward by the camming action of the pin 160 within the slot 162. Distalmovement of the finger 110 is caused by movement in the distal directionof the driver 132 with respect to the collet 108, as indicated by arrow180, due to the engagement between the driver travel slot 170 and thefinger pin 166. As the finger pin 166 moves in the distal direction, ittravels along the curvilinear collet cam slot 168. The linear drivertravel slot 170 accommodates radially inward movement of the finger pin166 in this regard.

[0072] The shapes of the finger cam slot 162 and collet cam slot 168 aredesigned such that the claw 116 at the distal end of the finger 110moves radially outward but remains in the same axial position.Furthermore, this movement of the finger 110 is accomplished bymaintaining the proximal collet 108 in a fixed relationship with respectto the valve body 112, while only displacing the proximal driver 132 ina distal direction, indicated by arrow 180. As such, only the proximaldriver cable 152 need be displaced. In the same manner, only the distaldriver shaft 140 need be displaced with respect to the distal colletshaft 128 to actuate the distal deployment fingers 106 (FIG. 4). Indeed,the distal and proximal collets 104, 108 remain stationary with respectto the valve 112 while the distal and proximal drivers 130, 132 aredisplaced toward one another. Likewise, the fingers 106, 110 areretracted radially inwardly by opposite movement of the drivers 130,132.

[0073] A sequence of steps in the delivery and deployment of a heartvalve utilizing the deployment mechanism 102 of FIG. 4 is seen in FIGS.7A-7F. FIG. 7A shows the deployment mechanism and heart valve in theirradially contracted configurations such that the entire assemblyresembles an elongated bullet for easy passage through the vasculatureof the patient, which is indicated by a generic vessel 190. Afterreaching the site of implantation, the valve 112 is permitted to selfexpanded under control of the deployment fingers. Namely, the proximaland distal drivers move axially toward one another permitting thefingers to pivot open which in turn allows the spirally wound expandableheart valve to unwind. The heart valve unwinds at a controlled rate intoits initial expanded configuration in contact with the surroundingtissue, as explained above.

[0074] Now with reference to FIG. 7C, the distal and proximal colletsare axially displaced away from one another so that the claws at the endof the fingers release from the ends of the heart valve. Subsequently,as seen in FIG. 7D, movement of the proximal and distal drivers awayfrom one another and with respect to the associated collets retracts thefingers inward a slight amount. FIG. 7E shows the deployment mechanismafter the collets have been axially advanced toward one another suchthat the claws at the end of the fingers are disposed within the heartvalve. In a final deployment step, as seen in FIG. 7F, the proximal anddistal drivers are again advanced toward one another and with respect tothe stationary collets so that the fingers pivot outward into contactwith the interior of the valve. The fingers force the valve outwardagainst the surrounding vessel and into its locked position. Thedeployment mechanism is then removed from the body by retracting thedeployment fingers and pulling the catheter along the guide wire.

[0075] FIGS. 8-10A illustrates a second alternative heart valve deliveryand deployment system 200 of the present invention that operates in muchthe same manner as the first two embodiments described above, althoughwithout pivoting deployment members. FIG. 8 illustrates the distal endof the system 200 with an expandable heart valve 202 held therewithin inits initial expanded configuration. FIG. 9 illustrates the distal end ofthe system 200 in the same configuration but without the heart valve.The system 200 includes a valve deployment mechanism 204 having aplurality of distal deployment pads 206 and a plurality of proximaldeployment pads 208 that engage the valve 202. The pads 206, 208 areshown in FIG. 8 on the exterior of the valve that enables theaforementioned control of the valve self-expansion. The pads 206,208 aredesirably relatively rigid and have rounded edges and/or are otherwisecoated with a material that prevents damage to the valve 202.

[0076] With specific reference to FIG. 9, each of the distal pads 206(preferably three) couples to a distal end cap 210 via a tension spring212. Likewise, each of the proximal pads 208 (preferably three) couplesto a proximal end cap 214 via a tension spring 216. The springs 212, 216exert radially inward forces on each of the pads 206, 208. The end caps210, 214 are mounted on separately movable shafts such that their axialspacing may be varied.

[0077]FIG. 10 illustrates the deployment mechanism 204 in a deploymentstage that converts the heart valve from its initial expandedconfiguration to its final, locked out configuration. FIG. 10A is alongitudinal sectional view taken along line 10A-10A of FIG. 10 andshows in detail the various components of the distal end of thedeployment mechanism 204. The distal end cap 210 is shown having arecess in its distal end that houses a plurality of shafts 220 aboutwhich coils each tension spring 212. The radial position of each pad 206is controlled by use of a distal wire tong 222 that is highly flexiblebut possesses column strength. Various nickel-titanium alloys arewell-suited for use as the wire tongs 222. Each tong 222 attaches to aninner side of a distal pad 206 and extends radially inward through a 90degree channel formed in the distal end cap 210 into fixed engagementwith a tong driver 224. The tong driver 224 attaches to a tong drivershaft 226 and is adapted for axial movement within the mechanism 204.The tong driver shaft 226 fits closely and is linearly slidable over adistal end cap shaft 228 fixed to a bore in the end cap 210. The distalend cap shaft 228 includes a lumen that closely receives a guidewire(not shown) used in positioning the heart valve at the site ofimplantation.

[0078] For the purpose of describing radial movement of the distal pads206 with reference to FIG. 10A, the reader will ignore the interpositionof a plurality of expansion bars 230 and brace links 232. Initially, thetong driver 224 is positioned to the right of where it is located inFIG. 10A and toward a distal slide collar 234. As such, the majority ofthe distal wire tong 222 is pulled through the distal end cap 210 suchthat its radial length is minimized, in contrast to the illustration.Therefore, the distal pads 206 are pulled radially inward and constrainthe heart valve in its spirally wound configuration. During regulatingself-expansion of the valve, the tong driver shaft 226 is advanced inthe distal direction with respect to the end cap shaft 228 such that thetong driver 224 moves to the left, pushing the distal wire tongs 222radially outward. Because of the column strength of the wire tongs 222,this operation forces the distal pads 206 radially outward against theinward forces of the tension springs 212, and permits the spirally woundvalve to unwind.

[0079] The final outward position of the distal and proximal pads 206,208 is seen in FIG. 9. FIG. 9 also illustrates the distal tong shaft 226and the distal end cap shaft 228, along with a proximal tong shaft 236and a proximal end cap shaft 238. Again, regulated self-expansion of theheart valve is accomplished by holding the end cap shafts 228, 238stationery, while displacing the tong shaft 226, 236 away from oneanother. Because the pads 206, 208 displace directly radially outward,there is no need for any accommodating axial movement as with theearlier pivoting finger embodiments.

[0080] After permitting the heart valve 202 to self-expand to itsinitial expanded configuration as seen in FIG. 8, the pads 206, 208 arerepositioned inside the valve and displaced outward to force the valvefurther outward into its final, expanded configuration. The position ofthe deployment mechanism 204 in this phase of the deployment operationis seen in FIGS. 10 and 10A. It will be noted that various components ofthe distal end of the deployment mechanism 204 will be numbered the sameon the proximal end.

[0081] As seen in FIG. 10A, each of the expansion bars 230 pivots at oneend about a point 239 on the respective slide collar 234. The oppositeend of each expansion bar 230 is free to pivot radially outward intocontact with the inner side of one of the pads 206, 208. Each brace link232 pivots at one end about a point 240 at the midpoint of an expansionbar 230, and at the other and about a pivot point 242 fixed with respectto one of the end caps 210. Axial movement of the end caps 210 towardone another causes the expansion bars 230 to pivot outward by virtue oftheir connection to the end caps through the brace links 232. Thisumbrella-like expansion structure provides substantial strength inforcing the heart valve 202 into its locked out position.

[0082] FIGS. 11A-11F illustrate several stages in the use of the secondalternative deployment mechanism 204 to deliver and deploy the heartvalve 202. FIG. 11A shows the assembly in its radially contractedconfiguration for delivery through the patient's vasculature. FIG. 11Billustrates release of the wire tongs to push the pads radially outwardwhich permits controlled self-expansion of a heart valve to its initialexpanded configuration. In FIG. 11C, the end caps are axially displacedaway from one another so that the pads disengage from the heart valve.In this regard, the tension provided by springs 212, 216 on the pads206, 208 provides an axial force that helps disengage the pads frombetween the valve and the surrounding tissue. At this stage, the wiretongs remain pushed radially outward. FIG. 11D shows the end caps in thesame axial position but after the wire tongs have been retracted suchthat the tension springs pull the pads inward. In FIG. 11E, the end capsare displaced axially toward one another which causes the expansion barsto pivot outward, and in addition, the pads moved inside the valve.Finally, FIG. 11F shows further end cap movement toward each other suchthat the expansion bars push the pads radially outward in conjunctionwith movement of the wire tongs so as to further expand the valve intoits locked out configuration.

[0083] FIGS. 12-13 illustrate the distal end of a further alternativeheart valve delivery and deployment system 300 that utilizes a gearingmechanism to expand a heart valve 302 into its initial and finalexpanded configurations. The system includes a deployment mechanism 304at the distal end of a shaft 306 having a distal end keeper 308 andretaining bar 310 and a proximal end keeper 312 and retaining bar 314.The axial spacing between the distal and proximal end keepers 308,312may be varied by movement of a connecting rod 316 (FIG. 12A) about whicha gear shaft 318 rotates. The heart valve 302 includes a sheet-likestent body bordered by a distal end 320, a proximal end 322, an outerside edge 324, and an inner side edge (not shown). The stent bodyfurther includes a distal gear track 326 extending circumferentiallyadjacent the distal end 320 and a proximal gear track 328 extendingcircumferentially adjacent the proximal end 322. The assembly rides overa guide wire 330 as mentioned previously.

[0084] With reference to FIGS. 12A and 13, details of the distal endkeeper 308 and retaining bar 310 will be described. The retaining bar310 extends axially in a proximal direction from the end keeper 308includes an inwardly formed tab 340 that engages a retaining slot 342 inan outer valve body winding 344 adjacent to the outer side edge 324.FIG. 12A illustrates in cross-section an inner winding 346 spaced fromthe outer winding 344 by a distance A. Of course, there may be more thantwo windings of the valve body in the contracted configuration thereof,as previously illustrated, for example, in FIG. 3A. Therefore, thedistance A varies as the valve unwinds.

[0085] The gear shaft 318 includes gear teeth 350 positioned to engagethe distal gear track 324. In a similar manner, a second set of gearteeth (not shown) is provided on the proximal end of the gear shaft 318to engage the proximal gear track 326. As mentioned, the gear shaft 318rotates about the connecting rod 316, which is held by a shaft retainer352 in a winding variance slot 354 in the distal end keeper 308. The endof the connecting rod 316 includes a flat or other such feature thatregisters with a cooperating feature in the winding variance slot 354 toprevent rotation of the rod, and provide a counter-torque to rotation ofthe gear shaft 318. The slot 354 is elongated in the radial direction topermit radial movement of the connecting rod 316 and accompanying gearshaft 318. Provision of a pusher 356 spring loaded against theconnecting rod 316by a spring 358 and set screw 360 maintains the gearteeth 350 in engagement with the gear track 324.

[0086] With reference to FIG. 12, it can be seen that the deploymentmechanism 304 remains circumferentially fixed with respect to the outerside edge 324 by virtue of the engagement between the retaining bar tabs340 and retaining slots 342. The gear shaft 318, on the other hand,circumferentially displaces the inner winding 346 in a direction thatunwinds the valve from its contracted configuration to its expandedconfiguration. During the unwinding process, the distance A between theouter winding 34 and the inner winding 346 is regulated by the springloaded pusher 356. The valve 302 may be converted to its initialexpanded configuration, and then further balloon expanded to a finallockout position, or the deployment mechanism 304 can fully expand thevalve into its lockout position. When the deployment mechanism 304 is nolonger needed, the end keepers 308, 312 are displaced axially apart suchthat the retaining bars 310, 314 disengage from their respectiveretaining slots 342. The deployment mechanism 304 can then be pulledover the guide wire 330 from within the deploying valve.

[0087] One advantage of such a deployment system 300 that utilizes agearing mechanism is that both unwinding and winding of the valve 302maybe easily controlled. Therefore, the surgeon may initially expand thevalve 302 but then contract it somewhat to modify its position prior tolocking it into its final expanded shape. In the worst case, the valve302 may be completely contracted into its thin profile and removed fromthe patient if desired, such as if the sizing is not optimal or fromother complications.

[0088]FIG. 14 illustrates in plan view an exemplary aortic valve body400 for use with a deployment mechanism similar to that shown in FIG.12. The valve body 400 includes a distal end 402, a proximal end 404, aninner side edge 406, and an outer side edge 408. A distal gear track 410is shown adjacent the distal end 402, while a proximal gear track 412extends along an outflow band 414. A plurality of leaflet openings 416is provided between the distal end 402 in the outflow band 414. A flaredmesh 418 separates the outflow band 414 from the proximal end 404. Asupplemental gear track 420 is provided adjacent the proximal end 404.The distal, proximal, and supplemental retaining slots 422, 424, 426 arelocated adjacent the outer side edge 408 and receive respectiveretaining tabs from the retaining bars of the deployment mechanism.Finally, lockout tabs 430 are provided to engage lockout channels 432and maintain the valve in its expanded configuration.

[0089] In contrast to the valve 302 shown FIG. 12, the flared mesh 418extends in the outflow direction and may be used to engage the ascendingaorta. To facilitate flaring of the mesh 418 during deployment of thevalve, the supplemental gear track 420 has a smaller number of openingsper length than the distal or proximal gear tracks 410, 412. Likewise,the gear shaft utilized in deploying the valve body 400 has three setsof gear teeth, one of which has fewer teeth per rotation so as to matewith the supplemental gear track 420. In this manner, the proximal end404 is expanded at a faster rate then either the distal end 402 oroutflow band 414 such that it flares outward with respect thereto.

[0090] While the foregoing describes the preferred embodiments of theinvention, various alternatives, modifications, and equivalents may beused. Moreover, it will be obvious that certain other modifications maybe practiced within the scope of the appended claims.

What is claimed is:
 1. A system for delivering and deploying anexpandable prosthetic heart valve, comprising: a catheter shaft having aproximal end and a distal end and a lumen therethrough extending alongan axis; a heart valve deployment mechanism extending axially from thedistal end of the catheter shaft, the deployment mechanism includingspaced apart proximal and distal deployment members; and an actuatingshaft extending through the lumen of the catheter shaft operable toactuate at least one of the proximal and distal deployment members. 2.The system of claim 1, wherein the deployment members are radiallymovable and comprise fingers each pivoted at one end thereof to thedeployment mechanism.
 3. The system of claim 2, wherein there are atleast two proximal deployment fingers and at least two distal deploymentfingers, and wherein the deployment fingers are axially movable.
 4. Thesystem of claim 1, wherein the deployment members are radially movableand there are two of the actuating shafts, a first actuating shaft beingoperable to radially displace the proximal deployment members and asecond actuating shaft being operable to radially displace the distaldeployment members, and wherein the first and second actuating shaftsare concentrically disposed to slide with respect one another.
 5. Thesystem of claim 1, wherein the deployment mechanism comprises a proximalcollet with respect to which the proximal deployment members pivot, anda distal collet with respect to which the distal deployment memberspivot, and wherein the proximal collet and distal collet are relativelyaxially movable.
 6. The system of claim 5, further including a firstactuating shaft extending within a cavity in the proximal collet and afirst driver attached thereto that acts upon the proximal deploymentmembers to pivot them with respect to the proximal collet, and a secondactuating shaft extending through the first actuating shaft and into acavity in the distal collet and having a second driver attached theretothat acts upon the distal deployment members to pivot them with respectto the distal collet.
 7. The system of claim 6, wherein each deploymentmember pivots about a point that is fixed with respect to the associatecollet and includes structure that engages cooperating structure on theassociated driver, and wherein axial movement of the driver rotates thestructure about the pivot point, thus rotating the deployment member. 8.The system of claim 6, wherein each deployment member has a pin fixedwith respect thereto that is received within a corresponding slot in theassociated driver, and each collet includes a plurality of pins fixedwith respect thereto that are received within corresponding slots in theassociated deployment members, and wherein axial movement of the driverdisplaces the pins fixed with respect to the deployment members andcauses the deployment members to pivot outward due to a camming actionof the deployment member slots over the collet pins.
 9. The system ofclaim 1, wherein each deployment member comprises a pad that is coupledto a respective proximal and distal end cap disposed along the cathetershaft, the pads being radially displaceable with respect to theassociated end cap, and wherein the proximal and distal end caps areaxially movable with respect to each other.
 10. The system of claim 9,wherein there are two of the actuating shafts, each shaft controlling aplurality of flexible tongs having column strength that extend betweenone of the end caps and attach to the associated pads, wherein axialmovement of each shaft shortens or lengthens the radial extent of theflexible tongs controlled thereby so as to radially displace theattached pads.
 11. The system of claim 1, wherein each deployment membercomprises a gear that engages a gear track on the heart valve.
 12. Thesystem of claim 1, further including a stabilization balloon provided onthe catheter shaft proximal to the deployment mechanism and sized toexpand and contact a surrounding vessel adjacent the site ofimplantation.
 13. The system of claim 12, wherein the stabilizationballoon is shaped so as to permit blood flow past it in its expandedconfiguration.
 14. The system of claim 13, wherein the stabilizationballoon includes multiple outwardly extending lobes.
 15. The system ofclaim 1, wherein the heart valve deployment mechanism is a modular unitcoupled to the distal ends of the catheter shaft and actuating shaft.16. A system for delivering and deploying a self-expandable prostheticheart valve to a site of implantation, comprising: a catheter foradvancing the heart valve in a contracted configuration to the site ofimplantation; means on the catheter for permitting the heart valve toself-expand from its contracted configuration to an initial expandedconfiguration in contact with the surrounding site of implantation; andmeans for regulating the rate of self-expansion of the heart valve. 17.The system of claim 16, further including: means for expanding the heartvalve from its initial expanded configuration to a final expandedconfiguration.
 18. The system of claim 17, wherein the means forexpanding the heart valve from its initial expanded configuration to afinal expanded configuration comprises a balloon.
 19. The system ofclaim 17, wherein the means for expanding the heart valve from itsinitial expanded configuration to a final expanded configuration is thesame as the means for regulating the rate of self-expansion of the heartvalve.
 20. The system of claim 19, wherein the means for expanding theheart valve from its initial expanded configuration to its finalexpanded configuration and the means for regulating the rate ofself-expansion of the heart valve comprise a plurality of radiallymovable fingers, wherein there is a plurality of distal radially movablefingers spaced from a plurality of proximal radially movable fingers,and wherein radial movement of the distal and proximal fingers isseparately controlled.
 21. The system of claim 20, wherein the means forexpanding the heart valve from its initial expanded configuration to itsfinal expanded configuration comprises a distal collet about which thedistal radially movable fingers pivot and a proximal collet about whichthe proximal radially movable fingers pivot, wherein the distal andproximal collets are axially movable with respect to each other.
 22. Thesystem of claim 21, wherein each of the fingers pivots about a pointfixed with respect to the associated collet.
 23. The system of claim 20,wherein each of the fingers has a flexible claw that engages the heartvalve, and wherein the means for expanding the heart valve from itsinitial expanded configuration to its final expanded configurationcomprises structure for maintaining the axial positions of flexibleclaws upon radial movement of the fingers.
 24. The system of claim 16,wherein the means for expanding the heart valve from its initialexpanded configuration to its final expanded configuration and the meansfor regulating the rate of self-expansion of the heart valve comprises agear mechanism that engages both the distal and proximal ends of theheart valve.
 25. The system of claim 24, wherein the heart valve is ofthe rolled type having multiple wound layers and the gear mechanismincludes a gear shaft that engages an inner layer of the spirally woundheart valve and a retaining bar that engages an outer layer of thespirally wound heart valve, wherein the distance between the gear shaftand retaining bar is adjustable.
 26. The system of claim 16, furtherincluding a stabilization device provided on the catheter proximal tothe means on the catheter for permitting the heart valve to self-expand,the device being sized to expand and contact a surrounding vesseladjacent the site of implantation.
 27. The system of claim 26, whereinthe stabilization device is a balloon shaped so as to permit blood flowpast it in its expanded configuration.
 28. A system for delivering anddeploying an expandable prosthetic heart valve to a site ofimplantation, comprising: a catheter for advancing the heart valve in acontracted configuration to the site of implantation; a stabilizationdevice provided on the catheter sized to expand and contact asurrounding vessel adjacent the site of implantation; and means on thecatheter distal to the stabilization device for expanding the heartvalve from its contracted configuration to an initial expandedconfiguration in contact with the surrounding site of implantation. 29.The system of claim 28, wherein the stabilization device is a balloonshaped so as to permit blood flow past it in its expanded configuration.30. The system of claim 29, wherein the stabilization balloon includesmultiple outwardly extending lobes.
 31. The system of claim 28, furtherincluding means for regulating the rate of self-expansion of the heartvalve.
 32. The system of claim 31, further including: means forexpanding the heart valve from its initial expanded configuration to afinal expanded configuration.
 33. The system of claim 32, wherein themeans for expanding the heart valve from its initial expandedconfiguration to a final expanded configuration comprises a balloon. 34.The system of claim 32, wherein the means for expanding the heart valvefrom its initial expanded configuration to a final expandedconfiguration is the same as the means for regulating the rate ofself-expansion of the heart valve.
 35. A method for delivering anddeploying a self-expandable prosthetic heart valve to a site ofimplantation, comprising: advancing the heart valve in a contractedconfiguration to the site of implantation; permitting the heart valve toself-expand from its contracted configuration to an initial expandedconfiguration in contact with the surrounding site of implantation; andregulating the rate of self-expansion of the heart valve.
 36. The methodof claim 35, wherein the step of advancing the heart valve in acontracted configuration to the site of implantation comprises providinga heart valve deployment mechanism that in one operating mode maintainsthe heart valve in the contracted configuration, and in anotheroperating mode regulates the rate of self-expansion of the heart valve.37. The method of claim 36, wherein the heart valve deployment mechanismincludes a plurality of proximal deployment members that engage aproximal end of the valve, and a plurality of distal deployment membersthat engage a distal end of the valve, and wherein coordinated radialmovement of the proximal and distal deployment members regulates therate of self-expansion of the heart valve.
 38. The method of claim 37,wherein the deployment members comprise fingers that pivot, and whereinthe method includes regulating the rate of pivot of the deploymentmembers to regulate the rate of self-expansion of the heart valve. 39.The method of claim 38, wherein the heart valve deployment mechanismincludes a proximal collet about which the proximal fingers pivot and adistal collet about which the distal fingers pivot, and wherein themethod includes displacing the proximal and distal collets axiallyduring pivoting of the proximal and distal fingers.
 40. The method ofclaim 35, wherein the heart valve deployment mechanism includes a gearshaft having a plurality of gear teeth that engage a gear track providedon the heart valve, wherein the rate of self-expansion of the heartvalve is regulated by regulating the rotational speed of the gear shaft.41. The method of claim 35, further including: expanding the heart valvefrom its initial expanded configuration to a final expandedconfiguration.
 42. The method of claim 41, further including providing acatheter-based valve deployment mechanism having deployment members thatboth regulate the rate of self-expansion of the heart valve and expandthe heart valve from its initial expanded configuration to its finalexpanded configuration.
 43. The method of claim 41, further includingproviding a catheter-based valve deployment mechanism having deploymentmembers that regulate the rate of self-expansion of the heart valve andan inflation balloon that expands the heart valve from its initialexpanded configuration to its final expanded configuration.
 44. Themethod of claim 43, wherein the valve inflation balloon is separate fromthe deployment mechanism and is introduced into the valve after at leasta partial expansion thereof.
 45. The method of claim 35, furtherincluding: stabilizing the heart valve in its contracted configurationadjacent the site of implantation prior to permitting the heart valve toself-expand.
 46. The method of claim 45, wherein the step of stabilizingthe heart valve comprises inflating a stabilization balloon.
 47. Themethod of claim 46, further including permitting blood flow past theinflated stabilization balloon.
 48. The method of claim 35, furtherincluding converting the heart valve from its initial expandedconfiguration to a smaller size.